Receiving gripper for a rapier loom

ABSTRACT

A receiving gripper for a rapier loom, wherein at least the moving part is made of a ceramic material.

[0001] The present invention relates to a receiving gripper for a rapierloom, said gripper comprising a component fitted with a clamping hookhaving a clamping surface and comprising a movable component fitted witha mating clamp face associated with said clamping hook's clampingsurface.

[0002] In receiving grippers of the above-mentioned type, the componentfitted with the clamping hook is mounted to a gripper tape or to a guideelement extension of the tape. The movable component is movable in sucha manner that its mating clamp face is advanced by a biasing springtoward the clamping hook's clamping surface so the mating clamp face maybe lifted off the hook's clamping surface. It is known in this respectto design the movable component as an element moving in the gripper'slongitudinal direction of motion (U.S. Pat. Nos. 4,736,777 and4,739,805), although said element also may be designed as a two-armlever pivoting about a pivot axis (U.S. Pat. No. 3,986,532). Whetherlongitudinally translatable or pivotable about a pivot axis, the movablecomponent is typically made of metal.

[0003] The objective of the present invention is to improve theoperational reliability of a receiving gripper of the above describedkind.

[0004] This problem is solved by making the movable component of ceramicmaterial.

[0005] The ceramic material provides relatively high rigidity andmechanical strength for the movable component which nevertheless, onaccount of its comparatively low density, possesses a relatively lowweight and a corresponding low angular moment of inertia. As a result,the movable element is relatively insensitive to vibrations oroscillations that otherwise might cause the mating clamp face toseparate from the clamping surface of the clamping hook, so that thegripper would accidentally open and lose the thread. Moreover the wearin the region of the mating clamp face and/or in the zone of a bearingand/or in the range of operation of a drive cam or the like shall besubstantially lower than if the movable component were made of a metal.As a result insets to increase wear resistance or mechanical strengthare not needed in the general case.

[0006] In a further embodiment of the invention, the component fittedwith the clamping hook also is made of ceramic. In this manner theoverall gripper weight may be reduced while simultaneously decreasingwear in the region of the clamping hook.

[0007] Further features and advantages of the present intention areexplained in the description below of the illustrative embodiment shownin the drawing.

[0008] The drawing is an exploded view a component which is firmlyaffixed to a gripper tape or to a guide element, the component beingfitted with a clamping hook, and another component being movablerelative to the former component.

[0009] The receiving gripper is only partly shown in the drawing andcomprises a component 10 mounted firmly to a gripper tape or to a guideelement extension of said tape. The forward end of this component 10 isfitted with a clamping hook 11 beginning at the tip and comprising atits rear a heel hook. This heel hook subtends a clamping surface 12which is paired with a mating clamp face 13 of a movable component 14.

[0010] The movable component 14 is a two-arm lever the head 15 of whichfaces the clamping hook 11 and is fitted with the mating clamp face 13.The end face of the head 15 is cross-sectionally contoured 16 to match acontour 17 on the inside of the clamping hook 11. The significance ofthese contours 16, 17 is explained in applicant's parallel patentapplication (internal file P 40197 DE). The clamping surface 12 and/orthe mating clamp face 13 on the other hand may be smooth or flat.

[0011] The second arm of lever 14 constitutes a drive element 18associated with an unknown stop. When the drive element 18 abuts againstsaid stop, the lever 14 is pivoted about its pivot axis and as a resultthe gripper is be opened, that is, the mating clamp face 13 is liftedoff the clamping surface 12. The two-arm lever 14 is fitted between thetwo arms with a bearing opening 19 by means of which it is mounted on abolt or a pivot stub 20 projecting from the component 10. An unshowncompression spring acts on said arm of the lever 14 within theoperational range of the drive element 18 and biases the lever 14 in amanner that the mating clamp face 13 is pressed against the clampingsurface 12 of the clamping hook 11. The lever 14 is designed in suchmanner that its center of mass is located at least approximately at thepivot axis defined by the bearing clearance 19 and the bolt or pivotstub 20. The purpose of this design is explained in a parallelapplication of this applicant (internal file P 40198 DE).

[0012] The movable component constituting the lever 14 is made of aceramic material. This preferably powder ceramic material is formed intothe shape of the lever 14 as shown and then sintered or baked.Present-day techniques allow manufacturing the lever 14 in its finalform, namely without the need for finishing work. That is, without theneed to finish the areas of the mating clamp face 13, the guide element16, the drive element 18 and the bearing opening 19. Ceramic materialoffers the advantage of comparatively low density. Moreover the ceramicmaterial offers high mechanical strength and great hardness.Accordingly, wear will be slight in the region of the mating clamp face13, of the drive element 18 and the bearing opening 19. Furthermore thedanger from vibrations is relatively low, in particular when the centerof mass is located in the vicinity of the pivot system 19, 20. As aresult, the required forces from the compression spring may bedecreased, and consequently wear also may be substantially reduced inthe region of the bearing.

[0013] In most cases the component 10 will be made of metal, the bearingstub 20 being fitted with a wear-resistant sleeve. Advantageously,however, the said component 10 also shall be made, together with theclamping hook 11 and the bearing stub 20, of a ceramic material.

[0014] The invention was described above by means of an illustrativeembodiment comprising a movable component in the form of a pivotinglever 14. Obviously, the invention also applies to movable receivinggripper components which cannot be pivoted and instead are reciprocatedlongitudinally in the manner illustratively known from U.S. Pat. Nos.4,520,851; 4,736,777 and 4,739,805. In such case, the drive element alsomay be made of ceramic material, and will be linked to thelongitudinally movable component to transmit the longitudinal motion.

1. A receiving gripper for a rapier loom, comprising a component (10)which is fitted with a clamping hook (11) having a clamping surface (12)and comprising a movable component (14) which includes a mating clampface (13) paired with the clamping face (12) of the clamping hook (11),characterized in that the movable component (14) is made of ceramicmaterial.
 2. Receiving gripper as claimed in claim 1, characterized inthat the movable component is a two-arm lever (14) one arm of which isfitted with a head (15) including the mating clamp face (13). 3.Receiving gripper as claimed in claim 1, characterized in that thesecond arm of the pivot lever (14) is fitted with a drive element (18).4. Receiving gripper as claimed in one of claims 1 through 3,characterized in that the pivot lever (14) is provided between its armswith a bearing opening (19).
 5. Receiving gripper as claimed in claim 4,characterized in that the center of mass of the pivot lever (14) issituated approximately at the bearing opening (19).
 6. Receiving gripperas claimed in one of claims 1 through 5, characterized in that thecomponent (10) together with the clamping hook (11) are made of ceramicmaterial.